Internal combustion engine



March 1941- M. TRANMELL, SR, ETAL 2, 7

INTERNAL COMBUSTION ENGINE Filed Aug. 24, 1959 2 Sheets-Sheet 1 1' FIG. 2.

INVENTORS EARL M. TRAMMELL SR. &

EARL TRAMMELL JR.

ATTORNEY v March 1941- E. M TRAffMELi- INTERNAL COMBUJ T ON ENGINE INVENTORS EARL M.TRAMMELL SR.& EARL MTRAMMELL JR.

BY Y ATTORNEY y Patented Mar. 4, 1941 INTERNAL O'ONIBUSTION ENGINE Earl M. Trammell, Sr., and Earl M. Trammell, Jr.,

St. Louis, Mo., assignors of twenty-five onehundredths to Irving J. McGuire, Dolgeville,

Application August 24, 1939, Serial No. 291,680

13 Claims.

This invention relates to improvements in internal combustion engines, and more particularly to improved methods of and means for increasing engine efficiency by imparting piston thrust to the crankshaft in a more eflicient manner than is the case with heretofore prevailing practice and equipment. The invention is physically realized in an improved piston and crankshaft connection.

Numerous attempts have heretofore been made to correct a known shortcoming in internal combustion engine operation, namely, the inefficient conversion of thermal energy to mechanical energy in a reciprocating type of internal combustion engine, during the period of peak combustion pressures near the beginning of the power stroke of the piston. These attempts have included in many instances, the provision of a plurality of separate connecting rods operatively relating a piston to its crankshaft, and in some cases the use of a connecting rod of variable length, being one susceptible of a telescopic action, against the loading of a compression spring or the like, during the period of highest combustion pressures. Such earlier attempts have, so far as is known, met with but indifferent success, or none at all, due in part to the use of certain elements in the connecting rod assemblies which failed to withstand the stresses of high speed engine operation. Still more fundamentally, the designs heretofore available have not succeeded in markedly increasing engine efficiency due to their failure to include a provision for efficiently translating to the crankshaft, the extraordinary degree of piston thrust existing during the early portions of the power stroke, or otherwise expressed, those existing during the relatively short period of peak combustion pressures on the piston. Expedients for the purpose noted which consist merely of a variable-length connecting rod assembly in which the rod elements are operatively related through a compression spring or the like, will serve in a certain measure to absorb, as kinetic energy in the spring, a portion of the tremendous thrust on the piston during the period of peak combustion; however, this energy, temporarily stored in the spring or the like, is not efiiciently converted due to the fact of the unloading of the spring considerably later in the power stroke of the piston and hence at a time too late in the stroke or cycle to translate most usefully, the peak of combustion pressure energy, into rotative movement of the crankshaft. The present invention, in the preferred example illustrated and to lie-described, utilizes a variable length connecting rod, but nevertheless goes considerably farther than the prior attempts hereinabove discussed, in imparting the peak combustion pressures in a much more efficient and advantageous manner to the crankshaft. This re- 6 sult constitutes one of the major objectives of the improved method and means to be described It is a further, broad and general object of the inventiomwhen applied to an internal combustion engine, to attain therein an improved 1.0

degree of operating efficiency; a more efficient conversion of the expansive energy of the burning charge and to attain a lower proportionate heat loss to the cooling fluid and exhaust gases.

A still further object, akin to the foregoing, 15 may be stated as attained in a more favorable crank leverage, during the period of peak combustion pressures on the piston.

Yet another object of the invention, and akin to that last stated, is attained in an engine which operates through a greater part of its Working cycle in accordance with existing principles and practice of engine piston and crankshaft relation, but which is characterized by means for temporarily introducing a much more favorable crank angle, during the period of peak combustion pressures, which step is followed by a later restoration of What may be termed a normal or basic crank angle.

Yet other objectives of the invention are found in the provision of a variable-length connecting rod, together with auxiliary means for translating the piston thrust to the engine power shaft, through an optimum crank angle during the period of peak combustion pressures.

Stated in terms of results attained, yet another object of the invention is realized in a reduction of detonation particularly in an engine constructed to provide higher compression ratios, or conversely stated, this object is attained by enabling an increase in compression ratio, without incurring a comparable increase in'tendency to detonation.

A still further object of the invention expressed in terms of structural embodiment, consists in the provision of a main crank together with an auxiliary crank, both of which may be operatively related through the same crank pin, and further embodying means for operatively coupling and disengaging the auxiliary crank in appropriate angular zones of crank rotation, for the better realization on extreme piston thrust.

An additional object of the invention is attained in means for selectively torsionallyconnecting an auxiliary crank to the usual main crank pin, or otherwise to the crankshaft, in an optimum ofiset angular position in order most advantageously to receive the maximum piston thrust during the period of peak pressures on the piston.

Yet a further object is attained in an arrangement of the means and elements referred to in preceding objects, in an extremely compact assembly so as to enable the structure added to embody the present improvements, to be confined within the axial dimensions of the crank cheeks, and to enable the assembly to operate within a circular zone about the crankshaft axis, which zone need be no larger than a circle described by existing crank elements.

A further object, somewhat ancillary to the foregoing, may be noted in the provision, in a variable-length connecting rod embodying a spring, of means tending to minimize any impact of the pants of the rod assembly, incident to unloading of the spring and the return of the rod to its normal or unloaded length.

The foregoing and numerous other objects of the invention will more clearly appear from the following detailed description of an illustrative embodiment of the invention, considered in connection with the accompanying drawings, in which:

Fig. 1 is a sectional elevation of a piston, cylinder, crankshaft and connecting rod assembly embodying the present improvements, and as viewed in a plane normal to the axis of the shaft; Fig. 2 is a sectional elevation of the assembly shown by Fig. 1, but taken at a right angle to the showing of Fig. 1, or in a plane parallel to that containing the crankshaft and cylinder axes; Fig. 3 is a view taken similarly to Fig. 1, but showing the parts in the relation they would assume during a period of peak combustion pressures; Fig. 4 is a fragmentary sectional elevation of a portion of the connecting rod assembly and crankshaft as same would appear when viewed along line 4-4 of Fig. 1, and Figs. -5, 6, 7 and 8 are diagrammatic showings, considered as if viewed similarly to the structural showing of Fig. 1, but illustrating the relative positions of different major elements of the assembly as they would appear, respectively, at the beginning of the power stroke; a short time later or during a period of peak combustion pressures; still later in the power stroke but close to the time of resumption of the normally prevailing relation of the major elements of the assembly, and as in Fig. 8, following completion of the power stroke and beginning of the next succeeding upstroke of the piston.

Referring now by characters of reference to the drawings, a power cylinder, which is or may be of any usual or conventional construction, is indicated at I0 and is provided for operation therein, with a power piston ll carrying the usual rings l 2 and a wrist pin I 3. The pin is arranged pivotally to engage a bearing structure l4 at the outer end of the connecting rod section I5. Inasmuch as ignition devices, if employed, as well as any valves, ports or the like, form no part of the present invention, they are omitted from the present drawings in the interest of clearness of illustration. It is understood however that the invention may be embodied in any engine operating according to any of the usual systems of cyclic function, and may consist, for example, of the usual four-stroke cycle engine.

The outer rod section I5 is continued toward the crankshaft into a yoke-like part including a pair of spaced arms l6 and I7. These arms are directed toward the shaft in substantially a straight line, to a zone somewhat beyond a pair of bosses l8 and I9. Below this zone the arms or furcations of this section of the rod assembly, are of a trend somewhat lateral of the line connecting the axis of piston pin l3 with that of the crank pin, later to be described. The laterally extending portions 25 and 26 resume their downward trend in a zone somewhat above the crank pin, as best appears from Figs. 1 and 3, and are provided at their innermost or otherwise free ends, with a two-part journal end such as 21 and 28, on the respective arms 25 and 26. These arms engage, in journalling relation, an auxiliary crankpin 30, the purpose and operative connection of which to the crankshaft are hereinaf-ter more fully described.

Operatively disposed between the furc-ations of the rod yoke is a block element 3|, which is connected to the opposite arms of the rod assemblies as through a pair of pivot elements 32 and 33, respectively journalled in the arms I! and it. These pivot elements are threadedly secured in tapped seats 34 and 35 respectively in the block 3|. For the sake of minimizing lateral projections, a recessed wrench seat such as 36, is provided in the outer end of each of the pivot pins 32 and 33, and a set screw 40 extends into the wall portion of block 3| to prevent unthreading of each of the pivot elements 32 and 33.

The block 3| is further provided with a bor 4| (Fig. 4) for the slidable reception of and engagement with a plunger '42, the latter being formed on or as a part of the inner journal end of the rod assembly, to be later described. The outer end of the plunger or stud 42 is threaded as at 43 for the reception of a holding nut 44. The nut may be of castellated type and pinned against unthreading rotation about the stud 42. Nut 44 either bears upon or may be formed integrally with a collar 45; in any case, the arrangement is preferably such that the collar and nut remain in assembly at all times, for reasons hereinafter better appearing. This collar is provided with a depending annular flange 46, the lower margins of which are chamfered or rounded as at 41. It will appear that, with the parts in their normal position as shown by Figs. 1, 2 and 4, .the flange 46 occupies an annular seat or groove therefor, designated at 50. By preference, the depth of the flange 46 is somewhat less than that of the groove 50 in which it seats, so that, as will better later appear when these parts are separated as shown by Fig. 3 for example, and later .are brought together, the close interfitting relation of the flange and groove serves to create a fluid pocket therebetween, and thus constitute a fluid cushion tending to minimize impact and the noise thereof, which might otherwise occur at times, depending upon conditions of operation, loading of the spring, later to be described, and other factors.

The pin or stud 42 as shown, is preferably an extended element of the rod assembly and preferably formed integrally with the crank .pin jour nal portion thereof. The latter consists in the present example, of a pair of spaced journalforming portions 5! and 52, being the parts of a bifurcate crank end of the rod, and between which is disposed the unidirectional drive connection (hereinafter described) for the "auxiliary crank pin 30 above referred to. 5| and 52 are split or divided at their lower ends, as indicated bythe bearing cap 54 secured to The rod arms the rod as by cap screws '55, with the interposition of suitable shims or the like as'may be desired.

Through the bearing construction just 'described, .the inner end of the connecting rod assembly is journalled 'on and pivotally engages the main crank 'pin 56, which is or may be of conventional or any suitable type, and is shown as bridging in the usual manner, the pairof crank cheeks 60 whichin turn are integrally formed with or fixedly secured to the body of the crankshaft 6|.

To provide for the variable-length characteristic of the main rod assembly, the stud 42, or more particularly stated, the lower bearing end of the rod assembly, serves to carry a heavy coiltype compression spring 62. This spring is seat-v ed at its inner or crankshaft end, in an annular seat 63, of a diameter and depth suchas to maintain the spring 62 substantially coaxial with the stud or pin 42. Similarly, the outer end of the compression spring has its abutment in an annular seat 64 formed on the undersurface of block 3|, the diameter of the recessed seat 64 being substantiallythe same as that of seat 63, and the spring being assembled between parts 63 and 3| under-at least a slight loading so as to obviate any tendency ofthe spring to shift its position with respect to the stud, block, and other elements of the rod assembly.

The journal'connection of the arms 25 and 26 with the pin 30, above briefly referred to, is completed through the bearing arrangement best shown by Figs. 1 and 3, as including an integral bearing half formedin the ends of each of the arms 25 and 25, and a removable bearing half for each arm, as indicated at 65, and retained in assembly by cap screws or the like 66, with the interposition of shims or the like between the halves of the bearing, as may be desired.

Proceeding now to describe further the manner of automatic selective connection of the auxiliary crank pin 30 to the crankshaft 6|, this is accomplished in the current example through an integral arm portion best appearing in section in Fig. 4 and designated generally at 10. This arm extends from its free end portion constituting an angularly offset crank element, to an enlargement particularly indicated at H and constituting the outer element of an overrun clutch or unidirectional drive, in the present example, between the auxiliary crank pin 38 and the main crank pin 56.

The enlargement is of a width or thickness substantially equal to the distance between the furcations 5| and 52 of the main rod assembly. It is preferably of a generally circular aspect transversely of the crankshaft, and one of its sides is provided with a relatively large recess or undercut portion 12. Stepped v inwardly or depthwise of the enlargement H, there is formed a second recess 13 shown by Fig. 4. The recess 13 is occupied in part by a disc-like enlargement 14 on the crank pin 56. The recess 13 is provided with tear-shaped pockets, there being preferably at least a pair thereof, in which are arranged hardeined rollers or the like 15, and which are biased toward the relatively restricted portions of the associated pockets as by coil springs 16. The rollers 15 are axially retained by the back wall of recess 13, particularly the walls of the roll-receiving pockets communicating therewith, and 'on the opposite side as by a closure 11, closely interfitting the recess 12, and

retained in assembly as by a plurality of screws 80.

The arrangement of the overrun clutch assembly consisting primarily of parts ll, 14, 15,

etc., is shown as adapted for a clockwise engine, is e., with the crankshaft rotating in a righthand direction as viewed in Figs. 1 and 3, and as indicated by the arrows in several of the figures. With the described arrangement of rolls 15 in the pockets therefor, it will appear that, as any substantial piston thrust is imparted through the arms 25 and 26, thence through auxiliary crank pin 30, and to the outer element H of the overrun clutch, this thrust is imparted to the disc M, hence to the main crank pin 56, in the same manner as if a wrench were applied clockwise to the pin itself. From this it results that the proportion of the piston thrust, which as will later appear is imparted to the auxiliary pin 30, is torsionally, rather than pivotally, applied to the crank pin. As to that part of the piston thrust which is applied through the furcations or arms 5| and 52, hence through spring 62, this component is applied to the main crank pin 56 in a manner which will be described as pivotal, or in the conventional and prevailing manner, as in the usual crankshaft end of rigid types of connecting rods.

It willhave further appeared from the arrangement of rollers 15 and the directioning of the pockets therefor, that as soon as the auxiliary pin 30 is relieved of any substantial degree of piston thrust, the tendency of the inner everrun clutch element 14, is to run ahead of the outer, with the eifect of carrying the rollers toward the larger portions of their respective pockets, thus operatively releasing the auxiliary crank pin from its power connection with the crankshaft 6|.

The operation of the assembly as a whole is thought to have been apparent in large measure from the foregoing description of the assembly of elements, but it may be noted for completeness that the loading of spring 62, as determined by its size, temper and othercharacteristics, is such that, throughout by far the greater part of the engine operating cycle, the main rod assembly comprised of elements l5,l6, ll, 3|, 62, 5!, 52, behaves exactly as if it were a single solid element of non-telescopic construction, with the result that, but for a restricted part of the cycle during the time of peak combustion pressures in the cylinder, piston thrust is transmitted to the crankshaft, and shaft thrust transmitted back to the piston through the rod assembly, without any deflection thereof occurring by reason of the elastic characteristic provided by the spring 62. In a four-stroke cycle engine, for example, such a condition prevails throughout the suction, compression and a part of the power strokes, and throughout the exhaust stroke of the piston. However, during times of highest piston loading in prevailing engine structures characterized by rigid connecting rods, the extreme thrust values are imparted through the rigid rod assembly at a time when the crank pin is in the least favorable angular position to realize on this thrust, namely, at or only very slightlybeyond the upper dead center crank position. It results from conventional arrangements that these peak pressures cannot be most advantageously realized on, since the piston, under the influence of peak combustion pressures, is not free to expand at a rate commensurate with the then-existing pressure values. The result is an excessive and unwarranted loss of heat units into the jacket and hence into the jacket-cooling fluid and, to a certain extent, later into the exhaust gases. It is obvious that if these heat losses can be reduced, engine operating efficiency is, pro tanto, increased.

The present invention in a large measure overcomes the substantial heat losses heretofore incurred during periods of peak combustion pressures by permitting the piston to descend at an accelerated rate, considered in respect to speed of crankshaft rotation, through the period in discussion. To this end the loading of spring 62 is so determined that as the piston moves, say, from the position shown by Figs. 1 and 5, to the position of parts indicated by Figs. 3 and 6, the high values of piston thrust then existing are transferred in large measure, primarily through the auxiliary pin 30. This is provided for by a substantial degree of compression of spring 62 enabling the pin 36 to assume its operative connection to the crank pin 56 through the action, heretofore described, of the overrun clutch elements. At the same time, what may be termed a minor proportion of the piston thrust is also being transmitted to the main crank pin 56 through the rod assembly including the part l5, arms is and i1, block 3| and spring 62, this ;thrust being that component which is imparted through the then-loaded spring.

From this relation of parts it will have appeared that the major portion of piston thrust is imparted to the crankshaft through an ar- ;rangement which, in effect, momentarily shifts the angular zone of the crank to a much more favorable angular position with respect to the crank circle, namely, in the region of 90 degrees or slightly greater, with respect to the cylinder axis.

The ensuing events are best illustrated by the series of diagrams of Figs. 5, 6, 7 and 8. From these it appears that as the piston H moves further outwardly or downwardly in its power stroke, and as the piston pressure diminishes very rapidly beyond the position shown by Fig. 6, by the time the piston has attained the position shown by Fig. '7, the spring 62 again starts to unload, so that, within the angular zone of crank movement shortly ahead of or slightly beyond the position indicated by Fig. 7, the overrun clutch is in process of disengagement, the spring 62 is in process of unloading, and the normal operative relation between piston II and the crank pin 56 is being resumed. This resumption of normal relation of parts is, by preference, completed some time during the latter part of the power stroke, and by the time the main crank pin has traversed its lower center position, normal operation again prevails, with the auxiliary crank 30, arms 25 and 26 and the outer element H of the overrun clutch, merely floating in assembly without being operatively engaged. From this point in the cycle until the next power stroke, the operation of the engine is or may be identical with that in prevailing engine constructions.

It will have appeared that during the time that the spring 62 is being loaded, the linear speed of piston H is distinctly accelerated; whereas during the period late in the power stroke, when the spring 62 is again being unloaded or restored to normal relation, a period the acceleration and deceleration being reckoned in respect to the piston speeds prevailing It will have appeared from the foregoing description of parts and the novel method involved in their operation, that our invention, broadly considered, involves the application of power from a reciprocating agency to a turning agency, at two angularly spaced pointsor zones onthe latter, instead of any single such zone, and serves to cause a maximum proportion of such power to shift desirably from one of these two zones to the other thereof. This offer the advantage, particularly in internal combustion engines, of enabling the piston to move at a linear speed which is much more in keeping with the speed possible by reason of the extreme pressures of the expanding charge during peak combustion periods. Thus considered, it becomes apparent that more of the energy of the expanding charge is enabled to be converted into mechanical energy, minimizing heat losses throughthe cylinder walls and enabling the use of higher compression without increase in detonation, since the piston is enabled to follow through during the early portion of the stroke, in better accord with the faster expanding action of the highly compressed and fully ignited mixture. It is further to be noted, at the time of highest combustion pressures, the aforesaid maximum portion of the power resulting from the burning charge is transferred to the secondary or auxiliary zone in the crank circle without loss of motion in relation to piston and crank travel. As reflected in an improved result, it will appear that engines employing the described means and method can be made smaller, that is, provided with either or both a shorter stroke and smaller bore for the same power output, than would be possible with conventional construction and practice. It will have further appeared that the invention serves to attain in all important respects, each and all of the several objects hereinabove specifically recited, as Well as those implied from the description of a preferred embodiment as herein given.

Although the invention has been described by making a somewhat specific reference to a selected structure'and practice, such description is to be understood solely in an illustrative sense, since many changes may be made in the parts and in the method of operation described, without departing from the full scope and intended spirit of the claims hereunto appended.

We claim as our invention:

1. In an internal combustion engine, a power cylinder, a piston operable therein, a connecting rod, a crank pin and means associated with the rod for applying through the rod, during an early part of a power stroke of the piston, a portion of the thrust then imparted to the piston'pivotally to the pin, and another such thrust portion torsionally to the pin.

2. In an internal combustion engine, a power cylinder, a piston operable therein, a connecting rod, a crankshaft having a crank pin, and means pivotally related to the connecting rod and normally pivotally associated with the crank pin, for torsionally applying a portion of piston thrust to the crank pin, during a period of, and in direct response to the efiect of peak combustion pressures in the cylinder.

3. In an internal combustion engine, a power cylinder,a piston operable therein, a crankshaft provided Witha crank pin, an extensible-contractible connecting rod, an auxiliary crank pin, both of said pins being pivotally connected with said rod, and means functionally responsive to high rates of cylinder pressure increase, for operatively locking the auxiliary pin against rotational displacement with respect to the crankshaft, during a portion of the power stroke of the piston.

4. In an internal combustion engine including a power cylinder, a piston operable therein, a crankshaft having a crank pin, a connecting rod of variable length, an auxiliary crank pin, both of said crank pins being associated with said connecting rod, and a releasable locking means arranged to interconnect the auxiliary pin and the crankshaft, during a portion of the power stroke of the piston.

5. In an internal combustion engine, a power cylinder, a piston operable therein, a variablelength connecting rod, a crank shaft provided with a crank, an auxiliary crank arm, pivotal connections respectively securing the rod to said crank andarm, and a unidirectional drive connection between the crank arm and the crankshaft.

6. In an internal combustion engine, a power cylinder, a piston operable therein, a crankshaft, a connecting rod of jointed type, between the piston and crankshaft, a main crank pivot, an auxiliary crank pivot, a connection from the rod to each pivot, and an overrun clutch operatively connecting the auxiliary crank pivot and main crank pivot. v

'7, In an internal combustion engine including a power cylinder, a piston operable therein, a crankshaft, a connecting rod of telescopic type, and including a compression spring in the rod assembly, a furcate portion on the connecting rod, pivotally engaging a crank element of the crankshaft, an overrun clutch disposed between the furcations of said rod end, and'an auxiliary crank pin carried by one element of the clutch, and being pivotally connected to the connecting rod in a zone substantially angularly spaced from said crank element in respect to the crank circle.

8. In an internal combustion engine, a power cylinder, a piston operable therein, a crank shaft, a connecting rod of contractile type operatively disposed between the piston and crankshaft and including a compression spring through which the elements of the rod are connected, and cushioning means associated with the rod assembly and including a pair of interfitting elements constituting a fluid cushion arranged to minimize impact upon extension of the spring.

9. The combination in an engine of reciprocating type, of a power cylinder, a piston operable therein, a crank, a connecting rod structure, means providing two zones of pivotal connection between the rod structure and the crank, said zones being spaced angularly from each other with respect to the crank circle, said rod structure and means including elements arranged to proportion between said zones of connection, the piston thrust imparted to the crank, in response to and in accordance with the instant pressures on the piston.

10. The combination in an engine of reciprocating type, of a power cylinder, a piston operable therein, a crank, a connecting rod structure, means providing two zones of pivotal connection between the rod structure and the crank, said zones being spaced angularly from each other within the crank circle, aid rod structure and means including elements arranged to proportion between said zones of connection, the piston thrust imparted to the crank, in response to and in accordance with the instant pressures on the piston.

11. The combination in an engine of reciprocating type, of a power cylinder, a piston operable therein, a crank, a connecting rod structure, and means providingtwo zones of pivotal connection between the rod structure and the crank, said zones being spaced angularly from each other with respect to the crank circle, said rod structure and means being arranged to impart piston thrust simultaneously through both of said zones of pivotal connection during a portion of the crank travel which is variable in accordance with duration, in reference to the stroke, of high pressures on the piston.

12. The combination in an engine of reciproeating type, of. a power cylinder, a piston operable therein, a crank, a connecting rod structure, and means providing two zones of pivotal connection between the rod structure and the crank, said zones being spaced angularly from each other with respect to the crank circle, said rod structure including means for translating a portion of piston thrust from one to another of said zones of pivotal connection, responsively to a relatively high rate of increase in value of piston thrust imparted to the rod structure.

13. In an engine of reciprocating type, a cylinder, a piston operable in the cylinder, a crank, a connecting rod structure, means providing two zones of-pivotal connection between the rod structure and crank, and means constituted by the first said means and part of the rod structure, for angularly displacing the lines of piston thrust application to the crank, solely and directly in response to the existence of high piston thrust values.

EARL M. 'IRAM'IMELL, SR. EARL M. 'IRAMMELL, JR. 

